From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3ED66309EFC; Tue, 18 Aug 2026 22:52:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787093547; cv=none; b=IP/c2P9HHqa1+jC6UICt5IDGxcC6V9JTg4vE2bXDPhns1mIVWrjPHP4HLbO5Ahlqr34B81hc/p9WE1Fmbsb68WCJDYVr63Nsf1TLs5Ucp/SlFKaIML589neSJJtmaXhZGxkbdcC3hBNc01Mt4oiqSoBke/BOjdeUPzKUzw58vBg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787093547; c=relaxed/simple; bh=z+Pg69X5kzndENcjRkyUsY4zMp68qmY07qCbm8JeyRc=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=FkKe8jdjhjmN2aC9EbeyvQJFygEnG+CrM7dA+0+cuFVEqZuDbqVD/OO2gelIenKEeskKAGGH0zddRggvOuZI48qIuQ5U342orYyr6Lt7uCcXVtbF6MUA76JbgkOXEjbpsgjqsz4vvWXu1uzv1Bin6Ov/OSkAZBqPh37uiXBhfZ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=b601v3Q1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="b601v3Q1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43DA71F000E9; Tue, 18 Aug 2026 22:52:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787093545; bh=Tr+DjgK7lF3lFwRjR19bOkQeerNhcsN0D8r3FOefsIo=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=b601v3Q1b2EQDyM3zY/J+fgai+mCtGCzjbjIWPtxi5CDqx2eZm9VFhewg2FJ48YPM LWYx7eJM9XbiiMwzBjZJ0F2UaILnyhN+6uXWA6U3A0wdslyh5GH2jlVz4WG95OFdka RwgzCqjUXxCQ4BDUxipZUEeO5GycpI5FCWQYQsHPllhHJt7iLaoM9iPRtsWhAZCwyE vxRfIO8aBMl4jw329AdgPYMagDwP9AiEO2V4QB9aKSmpzAroNmto/+k3sPyue34wNU qlRufYf9ACXISKHBEaTdblFWgkApiwqMgq/jrQ7Bv5fkop786ly0UrjTpJdGs5jVAo scx2rUXstmWxA== Date: Wed, 19 Aug 2026 07:52:21 +0900 From: Masami Hiramatsu (Google) To: Bradley Morgan Cc: Naveen N Rao , "David S . Miller" , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH] kprobes: use DEFINE_DEBUGFS_ATTRIBUTE for the enabled knob Message-Id: <20260819075221.18e9abdaab49d39f362ee0dc@kernel.org> In-Reply-To: <20260818014920.23870-1-include@grrlz.net> References: <20260818014920.23870-1-include@grrlz.net> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 18 Aug 2026 01:49:20 +0000 Bradley Morgan wrote: > This enabled knob is a disgusting terrible hack. It has rolled its > own read/write pair since 2007, writing '1' or '0' into a three byte > buffer by hand just to print a single character, with an XXX comment > begging debugfs for write callbacks on bool files. > DEFINE_DEBUGFS_ATTRIBUTE showed up in 2016 and does exactly that, so > the disgusting terrible hack has outlived its excuse for nine years. > Kill it, and the stale comment with it. Hm, OK, but please calm down. Just describe the technical reason here. > > The behavior does not change, except the write only accepts 0/1 now > instead of y/n/on/off, and nothing uses anything else. I think this comment is needed. Please add Signed-off-by. The code looks good to me. Thanks, > --- > kernel/kprobes.c | 43 +++++++++---------------------------------- > 1 file changed, 9 insertions(+), 34 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index bfc89083daa9..044c6b5fd2aa 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -3013,47 +3013,22 @@ static int disarm_all_kprobes(void) > return ret; > } > > -/* > - * XXX: The debugfs bool file interface doesn't allow for callbacks > - * when the bool state is switched. We can reuse that facility when > - * available > - */ > -static ssize_t read_enabled_file_bool(struct file *file, > - char __user *user_buf, size_t count, loff_t *ppos) > +static int kprobes_enabled_set(void *data, u64 val) > { > - char buf[3]; > + if (val) > + return arm_all_kprobes(); > > - if (!kprobes_all_disarmed) > - buf[0] = '1'; > - else > - buf[0] = '0'; > - buf[1] = '\n'; > - buf[2] = 0x00; > - return simple_read_from_buffer(user_buf, count, ppos, buf, 2); > + return disarm_all_kprobes(); > } > > -static ssize_t write_enabled_file_bool(struct file *file, > - const char __user *user_buf, size_t count, loff_t *ppos) > +static int kprobes_enabled_get(void *data, u64 *val) > { > - bool enable; > - int ret; > - > - ret = kstrtobool_from_user(user_buf, count, &enable); > - if (ret) > - return ret; > - > - ret = enable ? arm_all_kprobes() : disarm_all_kprobes(); > - if (ret) > - return ret; > - > - return count; > + *val = !kprobes_all_disarmed; > + return 0; > } > > -static const struct file_operations fops_kp = { > - .read = read_enabled_file_bool, > - .write = write_enabled_file_bool, > - .llseek = default_llseek, > -}; > +DEFINE_DEBUGFS_ATTRIBUTE(fops_kp, kprobes_enabled_get, > + kprobes_enabled_set, "%llu\n"); > > static int __init debugfs_kprobe_init(void) > { > -- > 2.47.3 > -- Masami Hiramatsu (Google)